This thesis describes a laboratory evaluation of gap-graded asphalt mix made with recycled concrete fine aggregate and, for purposes of comparison, natural sand fine aggregate. For purposes of mix design, specimens were prepared and tested in accordance with the Marshall procedure and the results were analysed with reference to design criteria given in SNI No. 1737-1989-F (LASTON), the Bina Marga (1986) specification for HRS Class B and the BS 594 (1985) specification for HRA. Tests for retained stability, indirect tensile strength and resilient modulus and resistance to permanent deformation in the wheel tracking apparatus were also conducted on specimens prepared at the optimum bitumen content indicated by the LASTON criteria. The recycled concrete fine aggregate had a high water absorption, 8,6 % by weight of aggregate as opposed to 2,8 % for the natural sand. This had a significant influence on the effective bitumen content of the mixes; absorbed bitumen content was determined to be 3.1 % and 1.2 %, by weight of aggregate, for the recycled concrete and natural sand mixes. None of the specifications evaluated results in a mix that is satisfactory in terms of full compliance with a wide range of important mix parameter. Mixes designed to SNI and Bina Marga (1986) criteria are likely to experience durability problems, in particular the mix containing recycled concrete, because of the relatively low effective bitumen content and bitumen film thickness. Mixes designed to BS 594 (1985) criteria are more satisfactory in term of compliance with durability criteria but have excessively low air voids content. At the optimum bitumen content indicated by LASTON criteria, the mix made with natural sand failed to meet the retained stability criterion; the mix made recycled concrete was adequate. Indirect tensile strength and resilient modulus values at various temperatures were comparable for both mixes; at 45 degree C and 60 degree C in the wheel tracking test, the performance of the mix made with natural sand was superior to that of the mix made with recycled concrete aggregate. There appear to be no technical reasons why recycled concrete aggregate should not be used as the fine aggregate component of gap-graded mix. However, given the high absorption of this material, care shoild be taken in mix design to ensure that the bitumen content is sufficient to ensure satisfactory long-term durability.

Deskripsi Alternatif :

This thesis describes a laboratory evaluation of gap-graded asphalt mix made with recycled concrete fine aggregate and, for purposes of comparison, natural sand fine aggregate. For purposes of mix design, specimens were prepared and tested in accordance with the Marshall procedure and the results were analysed with reference to design criteria given in SNI No. 1737-1989-F (LASTON), the Bina Marga (1986) specification for HRS Class B and the BS 594 (1985) specification for HRA. Tests for retained stability, indirect tensile strength and resilient modulus and resistance to permanent deformation in the wheel tracking apparatus were also conducted on specimens prepared at the optimum bitumen content indicated by the LASTON criteria. The recycled concrete fine aggregate had a high water absorption, 8,6 % by weight of aggregate as opposed to 2,8 % for the natural sand. This had a significant influence on the effective bitumen content of the mixes; absorbed bitumen content was determined to be 3.1 % and 1.2 %, by weight of aggregate, for the recycled concrete and natural sand mixes. None of the specifications evaluated results in a mix that is satisfactory in terms of full compliance with a wide range of important mix parameter. Mixes designed to SNI and Bina Marga (1986) criteria are likely to experience durability problems, in particular the mix containing recycled concrete, because of the relatively low effective bitumen content and bitumen film thickness. Mixes designed to BS 594 (1985) criteria are more satisfactory in term of compliance with durability criteria but have excessively low air voids content. At the optimum bitumen content indicated by LASTON criteria, the mix made with natural sand failed to meet the retained stability criterion; the mix made recycled concrete was adequate. Indirect tensile strength and resilient modulus values at various temperatures were comparable for both mixes; at 45 degree C and 60 degree C in the wheel tracking test, the performance of the mix made with natural sand was superior to that of the mix made with recycled concrete aggregate. There appear to be no technical reasons why recycled concrete aggregate should not be used as the fine aggregate component of gap-graded mix. However, given the high absorption of this material, care shoild be taken in mix design to ensure that the bitumen content is sufficient to ensure satisfactory long-term durability.